// Pair.cs
//
// Copyright (c) 2009 Jérémie Laval and Sylvain Marchand
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
//
//

using System;

namespace Bechamel
{
	
	public class Pair
	{
		object car;
		object cdr;
		bool isAList;

		// To check for empty list we will use reference equality
		public static readonly Pair EmptyList = new Pair(null, null);
		
		public object Cdr {
			get {
				return cdr;
			}
			set {
				cdr = value;
			}
		}
		
		public object Car {
			get {
				return car;
			}
			set {
				car = value;
			}
		}

		public bool IsAList {
			get {
				return isAList;
			}
		}

		public Pair(object car, object cdr): this(car, cdr, false)
		{
		}
		
		public Pair(object car, object cdr, bool isAList)
		{
			this.car = car;
			this.cdr = cdr;
			this.isAList = isAList;
		}
	}
}
